You guys should really add this to the top of the Modified Content sticky:
"Try another server. The one you're on may not be updated."
I've been trying to join my clan's server and it appears it wasn't up-to-date. I had to remote into the server and run the dedicated server exe file to update it. Looks like your autoupdater doesn't always work.
I can now play on my clan's server without the Modified Content error.
Now, if I can just get the damn thing populated! We had about a dozen or so in there for a couple rounds, then we went for a good hour and a half until we had enough to start the game, then someone left